Method and Its Apparatus for Detecting Defects

ABSTRACT

In the present invention, to make corrective matching thereof, it is designed as follows; position effect of defects coordinates, which are output from an inspection apparatus, is allowed, coordinates of inspected data are mutually corrected, and a state of coincidence or non-coincidence among a plurality sets of inspected data is output or displayed. Inspection data is designed to include kinds, kinds difference and dimension of defects. A state of coincidence or non-coincidence between inspected data is designed to be output or displayed appropriately, by kinds or dimensions, or by a grouping thereof, of a defects object. The same sample is inspected by every time of passing a production step, and a state of data increase or decrease, or coincidence or non-coincidence between the inspected data is designed to be output or displayed.

INCORPORATION BY REFERENCE

The present application claims priority from Japanese applicationJP2006-103732 filed on Apr. 5, 2006, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

The present invention relates to a defects inspection apparatus of amagnetic disk substrate or a semiconductor wafer or the like, inparticular, relates to, in a method for mutually comparing or checking aplurality sets of a detected data obtained by repeated inspection of thesame substrate, or a plurality sets of an inspected data obtained byinspection of the same substrate using an inspection apparatus beforeand after process treatment, a defect inspection method, wherein a stateof defects coincidence or non-coincidence is output or displayed; and anapparatus therefor.

As a magnetic recording medium used in a hard disk apparatus, a disksubstrate vapor deposited with a magnetic substance is used. Data ismagnetically recorded and reproduced on and from this disk substrate, bymagnetization with a magnetic head. Recently, with improvement ofrecording density in a hard disk apparatus, spacing (hereafter referredto as a flying height) between a head for recording and writing(hereafter referred to as a head) and a disk substrate has extremelybeen narrowed as small as several tens nm to several nm; therefore,presence of depression/protrusion defects larger than the flying height,on this disk substrate, makes the disk substrate and the head contacted,and causes failure of a hard disk apparatus. Therefore, in a statebefore vapor deposition of a magnetic substance, it is important toinspect presence or absence of the above defect, and not to flow adefect product to the downstream steps.

These defects include crystal defects embedded inside a disk substratematerial, residue of abrasive grains, or fine scratch (scratch or thelike) generating in polishing for improvement of flatness of a disksubstrate, or foreign matters adhering in cleaning or drying or thelike.

Foreign matters adhered on a surface can be removed or prevented byre-cleaning, cleaning-up of surrounding atmosphere or the like. However,crystal defects or scratch or the like cannot be corrected, resulting inhandling as a defect product; therefore, to ensure high yield and highreliability of a hard disk apparatus, early stage removal of a disksubstrate having such defects is important. In addition, also aftervapor deposition of a magnetic substance, the above defects areconsidered to generate by certain causes, therefore surface stateinspection is also necessary.

In the above inspection apparatus of a surface state, it is naturally animportant item to remove defect goods of a disk substrate inspected, butalso to monitor an apparatus state so as to maintain good condition,even in an apparatus to produce a disk substrate, to improve yield. Itis also an important item to analyze, based on the above detectionresult of an inspection apparatus, whether or not such defects arederived from production apparatus failure, or foreign matters adhered inconveying between production apparatuses. Analysis based on defects dataoutput from an inspection apparatus requires understanding of the placewhere the defects generated, along with positions, shapes and kinds ofthe defects.

In a conventional surface inspecting apparatus, as described inJP-A-2004-170092, there is a system for displaying a defect map based ondefects kinds and sizes, from characteristics of defects detected.Position information (coordinates) of defects obtained by detectionusing an inspection apparatus, is position information in a rotationdirection and in a radius direction. Because a hard disk apparatusrotates a circular plate-like disk substrate in high speed, in a stateof maintaining only a small gap with a magnetic head, uniformity of asurface shape of the disk substrate is required. Therefore, a cut edgesuch as a notch cannot be provided, like a wafer used in production of asemiconductor device. In addition, because whole surface of a disksubstrate is used for magnetic recording, pattern recording for a servodrive or the like, marking at the outer circumference or innercircumference is usually not allowed. Therefore, in general, coordinatestandard cannot be set in a disk substrate. Therefore, in an inspectionapparatus of a disk substrate, an inspection start position, in a fixedstate of a disk substrate at an inspection apparatus, is used as thestandard, and data of coordinates in a rotation direction and in aradius direction, namely position of a polar coordinate system, isprepared based on this standard.

Therefore, in a state that a disk substrate is mounted on an inspectionapparatus, the coordinates are controlled, which makes finding outobjective defects easy. However, once a disk substrate is taken out fromthe inspection apparatus, the coordinates are reset, and thus, even whenthe same disk substrate is re-inspected, coincidence of coordinates withthe previous inspection results is difficult; that requires comparisonusing defects map output by each inspection, on difference in kinds,coordinates and number of defects by each of the inspections. Therefore,in the case of a plurality of inspections, and coordinate origins ofdefects maps output by each of the inspections do not coincide, aproblem is raised that determination on whether or not the defects arethe same defect, or foreign matters adhered this time is ambiguous, frominformation on the defect maps outputs.

In addition, also in carrying out surface inspections before and after aproduction step, insufficient inspected data makes discriminationdifficult whether or not defects are newly generated in the productionstep, or generated in previous steps from the production step thereof,resulting in correct determination impossible on a state of a productionapparatus. Furthermore, in the case of defects matching in an apparatusother than surface inspection apparatus, which is capable of similarlyoutputting defects in a rotation direction and in a radius direction(for example, an inspection apparatus of magnetic characteristics,described in JP-A-2000-57501), coordinate coincidence is difficult;therefore, even by analysis back to the previous steps, when criticaldefects generates, sufficient analysis may be inhibited becausecoordinates provide no coincidence, or insufficient matching.

As described above, a conventional inspection apparatus gave noconsideration of use of inspected data for analysis, which raised aproblem of inability of mutual determination by inspected data.

Because there was no consideration of inspected data of detected resultsfor mutual utilization, in an inspection apparatus for inspecting acircular sample such as a disk substrate, which cannot prepare positionstandard, inspected data could not effectively be utilized.

SUMMARY OF THE INVENTION

The present invention provides a method for defects inspection, which iscapable of mutual utilization of a plurality sets of an inspected data,by correction of coordinates of a plurality sets of an inspected data,in the case of processing each inspected data obtained by a pluralitynumbers of inspections on the same disk substrate, in inspecting a disksubstrate, which cannot set position standard, and is provided with dataprocessing function, so that inspected data is effectively utilized; andan apparatus therefor.

Namely, in the present invention, it is designed, in a method forinspecting a sample, to have the following steps for obtaining positioninformation, in a first coordinate system, of a first defects groupdetected by detecting the first defects group on a sample, by inspectingthe sample under a first condition; obtaining position information, in asecond coordinate system, of a second defects group detected bydetecting the second defects group on a sample, by inspecting the sampleunder a second condition; correcting error of relative positioninformation on the first defects group and/or the second defects group,which generate by misalignment between the first coordinate system andthe second coordinate system; checking the first defects group and thesecond defects group, having error of the relative position informationcorrected; and outputting the checked results.

In addition, in the present invention, it is designed, in a method forinspecting a sample, to have the following steps for: obtaining positioninformation on a first defects group detected, relative to a firstposition standard on a sample, by detecting the first defects group onthe sample by inspecting the sample under a first condition; obtainingposition information on a second defects group detected, relative to asecond position standard on a sample, by detecting the second defectsgroup on the sample by inspecting the sample under a second condition;calculating misalignment amount between the first position standard andthe second position standard, using position information on the firstdefects group, relative to the first position standard, and positioninformation on the second defects group, relative to the second positionstandard; correcting position information on the first defects groupand/or position information on the second defects group, based on thecalculated misalignment amount; checking the first defects group and thesecond defects group, having the position information corrected; andoutputting the checked results.

Further, the present invention is provided with the followingconstitutions; a table unit for mounting, rotating and as well asmoving, in one axial direction, a sample; a lighting unit forilluminating light from an oblique direction to the sample which ismounted on the table unit and rotating and moving in one axis direction;a detection unit for detecting, by focusing, scattered light from thesample lighted by the lighting unit; a defects extraction unit forextracting defects present on the sample, by processing signals detectedby the detection unit; a defects information extraction unit forextracting information on defects extracted by the defects extractionunit; a memory unit for memorizing information on defects extractedpreviously; a defects information correction unit for correctinginformation on the defects extracted by the defects informationextraction unit, and information on defects extracted previously, whichwas memorized in the memory unit; a defects information checking unitfor checking information on the defects extracted by the defectsinformation extraction unit, which was corrected by the defectsinformation correction unit, and information on the defects extractedpreviously, which was memorized in the memory unit; and an output unitfor outputting result checked by the defects information checking unit.

According to the present invention, in the case of inspecting a circularsample such as a disk substrate, which cannot prepare position standard,processing of the inspected data based on the same standard exertseffects of enabling mutual comparison or check from a plurality sets ofa inspected data, and correct understanding of a state of increase ordecrease in defects data, coincidence or non-coincidence of inspecteddata, and understanding of defects generating state, early stage findingof critical defects, and correct understanding of production apparatuscondition.

These and other objects, features and advantages of the invention willbe apparent from the following more specific description of preferredembodiments of the present invention, as illustrated in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing outline constitution of an apparatusfor inspecting defects of a disk substrate according to an embodiment ofthe present invention.

FIG. 2 is a drawing showing an output example of data obtained byinspection using an apparatus for inspecting defects of a disk substrateaccording to the present invention.

FIG. 3 is a process flow diagram showing an example of a process flowfor producing a disk substrate of the present invention.

FIG. 4 is a drawing showing an example of defects on a disk substrate,which is a detection object in the present invention.

FIG. 5 is a cross-sectional view of a disk substrate and a magnetichead, showing positional relation between the magnetic head levitatingabove a rotating disk substrate, and foreign matters adhered on thesurface of the disk substrate.

FIG. 6 is a flow diagram explaining inspection procedure of a disksubstrate by the present invention.

FIG. 7A is a drawing map-displaying a distribution state of defects on adisk substrate as a result of a first inspection; FIG. 7B is a drawingmap-displaying a distribution state of defects on a disk substrate as aresult of a second inspection; FIG. 7C is a drawing map-displaying adistribution state of defects on a disk substrate after rotationposition correction for the second inspection result; FIG. 7D is adrawing map-displaying a distribution state of defects on a disksubstrate, which shows a comparison state of coordinates on the firstinspection result, and the second inspection result after rotationposition correction; FIG. 7E is a drawing map-displaying a distributionstate of defects on a disk substrate, which are determined ascoincident, based on a comparison result of coordinates on the firstinspection result and on the second inspection result after rotationposition correction; and FIG. 7F is a drawing map-displaying a state ofdefects on a disk substrate, which are determined as non-coincident,based on a comparison result of coordinates on the first inspectionresult and on the second inspection result after rotation positioncorrection.

FIG. 8(a) is a drawing explaining rotation position correction, andmap-displaying a distribution state of defects on a disk substrate as aresult of the first inspection; and FIG. 8(b) is a drawing explainingrotation position correction, and map-displaying a distribution state ofdefects on a disk substrate as a result of the second inspection.

FIG. 9 is a drawing explaining rotation position correction, andmap-displaying mid-flow of rotation position correction in FIG. 8.

FIG. 10 is a flow diagram showing procedure of rotation positioncorrection processing according to the present invention.

DESCRIPTION OF THE EMBODIMENTS

The present invention relates to a method for defects inspection, whichis capable of mutual utilization of inspected data obtained byinspections using a plurality of inspection apparatuses, by correctionof coordinates of a plurality sets of an inspected data, in the case ofprocessing each inspected data obtained by inspections using a pluralityof inspection apparatuses on the same disk substrate, in inspecting adisk substrate, which cannot set position standard, and is provided withdata processing function, so that inspected data is effectivelyutilized; and an apparatus therefor.

The present invention can be used, in the case of inspecting on the sameinspection step, using a plurality of defects inspection apparatuses,for evaluation of variation (instrumental error) in detectionsensitivity among a plurality of defects inspection apparatuses, bychecking inspected data among each of the inspection apparatuses, andmatching sensitivity among each of the defects inspection apparatuses;in addition, the present invention can also be applied to the case ofchecking defects data obtained by inspecting in a plurality ofinspection steps, using a plurality of defects inspection apparatuses,which have sensitivities thereof matched similarly. Furthermore, thepresent invention can also be applied to the case of checking inspecteddata output from a defects inspection apparatus and other kinds ofinspecting apparatuses (for example, a glide test apparatus, a certifytest apparatus or the like).

The embodiments of the present invention will be explained below usingdrawings.

As embodiments relevant to the present invention, cases for detection ofthe same disk substrate by a plurality of inspection apparatuses,evaluation and adjustment of defects detection sensitivity of each ofinspection apparatuses, by checking of inspection results by each of theinspection apparatuses, will be explained using FIGS. 1 to 9.

FIG. 1 shows constitution of the defects inspection apparatus 1000 inthe present invention. The disk substrate 1 is fixed on the rotationstage 2 by a method not shown. The rotation stage 2 is capable ofcontrolling rotation number by the rotation stage control unit 3, aswell as detecting position in a rotation direction. The rotation stage 2is capable of moving in a horizontal direction by the stage 4. The stage4 is capable of controlling movement amount in a horizontal direction bythe linear stage control unit 5, as well as detecting position in aradius direction. Light is illuminated from an oblique direction of thedisk substrate 1, by the lighting apparatuses 6 and 7. A surface stateof the disk substrate 1 can be detected using the detector 10, byarrangement of the objective lens 9 above the disk substrate 1. As thedetector 10, a photoelectric transducer is used. The lightingapparatuses 6 and 7 illuminate the disk substrate 1, using any one of,or both of the lighting apparatuses 6 and 7, under control of thelighting exchange apparatus 8.

In the present embodiment, explanation was given on a detecting systemfrom upside, by illumination of light from an oblique direction,however, a method for detecting defects is not especially limited, andincludes detection from an oblique direction by lighting from upside bya method not shown, or detection from upside using a circumference-likelighting.

The control unit 12 is constituted by the defects detection 11 fordetecting defects by processing detection signals from the detector 10;the defects classification determination unit 51 for determining kindsof defects detected by the defects detection 11; the positioninformation detection unit 52 for determining coordinates from positionsdetected by the rotation stage control unit 3 and the linear stagecontrol unit 5; the critical defects determination unit 55 fordetermining whether or not defects detected are critical defects; thestage control unit 56 for controlling rotation and linear movementstages; the lighting control unit 57 for exchanging lighting of any oneof or both of lighting apparatuses 6 and 7 under control of the lightingexchange apparatus 8; the memory 50 for memorizing inspected data; theMPU 58 for controlling these; and the bus 59.

The data processing unit 60 is joined with a plurality of defectsinspection apparatuses including the defects inspection apparatus 1000,and carries out various data processing by receiving results processedby the control unit 12 of each of the defects inspection apparatuses. Asone of these various data processing, axis misalignment of polarcoordinate data (misalignment of an original point of polar coordinateand misalignment of a base line in a rotation direction, which aretentatively set on a detection object disk substrate) among each ofdefects inspection apparatuses are corrected by the rotation positioncorrection 61 (hereafter described as rotation position correction), byinput of coordinate data sets of defects detected by a plurality ofdefects inspection apparatuses, and inspected data from each of thedefects inspection apparatuses having axis misalignment of coordinateddata corrected are mutually checked by the defects checking unit 62.Furthermore, in the defect criticality determination unit 63, defectcriticality is determined based on the inspected data thus mutuallychecked.

It should be noted that the data processing unit is also capable ofcarrying out rotation position correction of polar coordinate data ofdefects detected by each time of the inspections, by the rotationposition correction unit 61, after receiving data inspected in aplurality of times by the defects inspection apparatus 1000, mutuallychecking of defects data detected by each time of the inspections,having axis misalignment of coordinate data corrected, by the defectschecking unit 62, and determination of defects criticality based oninspected data mutually checked, in the defects criticalitydetermination unit 63.

The input apparatus 13 is one for inputting inspection conditions ornecessary items and the like. The monitor 14 is capable of displayingdefects detected, and supporting screens in input. The printer 15 iscapable of outputting defects coordinates, maps thereof and the like.The database 16 is capable of accumulating whole data of resultsprocessed by the control unit 12, and providing free reading andwriting.

Operation of defects detection in the defects inspection apparatus 1000shown in FIG. 1 will be explained. Firstly, onto the surface of the disksubstrate 1 mounted on the rotation stage 2, light is illuminated froman oblique direction, by selection of any one of or both of the lightingapparatuses 6 and 7, by the lighting exchange apparatus 8, under controlof the lighting control unit 57. In this state, the rotation stage 2mounted with the disk substrate 1, rotates under control of rotationnumber by the rotation stage control unit 3; and the stage 4, which iscontrolled by the linear stage control unit 5 in view of movement amountin a horizontal direction, moves in a horizontal direction. The stage 4moves in an amount of spot width, by each one rotation of the rotationstage 2.

Onto the surface of this rotating disk substrate 1, light havingspot-like cross-section of light bundle is illuminated by selection ofany one of or both of the lighting apparatuses 6 and 7, by the lightingexchange apparatus 8 under control of the lighting control unit 57. Inthe case where defects are present on the surface of the rotating disksubstrate 1, illuminated light generates reflection or scattering lightfrom the defects, and a part thereof is focused by the objective lens 9and detected by the detector 10.

Signals detected by the detector 10 are input to the control unit 12,after A/D conversion, and subjected to signal processing by the defectsdetection unit 11, so that signals stronger than preset signal level aredetected as defects signals. On the other hand, to the defects detectionunit 11, rotation angle information (θ) of the rotation stage 2, andposition information (R) of a horizontal direction of the stage 4 areinput, so that position information of the disk substrate 1 generated bythe defects signals detected can be obtained as information, in a polarcoordinate form of an R-θ coordinate system. These defects detectionsignals and position information on defects are stored and memorized inthe memory 50. Defects detected are subjected to defects classification,by the defects classification determination unit 52, based on signallevels detected, continuity of defects positions, size of defectspositions in a width direction or the like. In addition, in the criticaldefects determination unit 55, in the case where results of defectclassified by the defects classification determination unit 52 arecoincident with preset defects classification, determination to becritical defects is given.

FIG. 2 shows an example of data output from the defects inspectionapparatus 1000. Numerals shown in FIG. 2 are only examples of defectsnumber, defects kinds, coordinates (polar coordinates) of defects in aradius direction (R direction) and a rotation direction (θ), defectsshape of length and width, detection intensity from defects detected bythe detector 10. These pieces of information can be accumulated in thememory 50, in response to each of the defects numbers. This data isnaturally accumulated also in the database 16.

FIG. 3 explains outline of a production method for a disk substrate usedin a hard disk apparatus. Production steps of a disk substrate arelargely divided into a former half part till the formation step of asubstrate before vapor deposition of a magnetic substance, and a laterhalf part till the formation step of a medium processed with a magneticfilm.

The substrate is prepared via the shape fabrication step 100 forfabricating outer diameter and inner diameter, from material such asglass or aluminum alloy or the like; the polishing step 101 which iscapable of making both surfaces flat; the cleaning step 102 for removingforeign matters adhered; and the inspection step 103 for inspecting asurface state of the completed substrate.

The medium is prepared via the texture fabrication step 104 forfurnishing a texture on the surface of the substrate; the cleaning step105; the magnetic substance film formation 106 for vapor deposition of amagnetic film by sputtering or the like; the lubrication layer filmformation 107; the polishing 108 for polishing the medium surface bypolishing or varnishing; the glide test 109 for inspecting protrusionson the surface, which are harmful to a magnetic head; and the certifytest 110 for inspecting recording failure by carrying out reproductionby a magnetic head.

Before and after each of the steps, inspection is carried out by thedefects inspection apparatuses 1000-1 to 1000-5, so as to eliminatedefects products based on inspection results. The inspection results byeach of the defects inspection apparatuses 1000-1 to 1000-5 are sent tothe data processing unit 60 to be subjected to correction, by therotation position correction unit 61, on coordinate data error ofdefects detected by each of the inspection apparatuses 1000-1 to 1000-5,caused by misalignment of a coordinate system in each of the inspectionapparatuses 1000-1 to 1000-5, and subjected to mutual check of data fromeach of the defects inspection apparatuses, having corrected error ofcoordinate data caused by misalignment of a coordinate system by thedefects checking unit 63. In this way, a step where new defectsgenerated can be specified. Furthermore, in the defect criticalitydetermination unit 63, criticality of defects is determined based oninspected data after mutually checked.

In addition, data processed at the data processing unit 60, and dataobtained by inspection by each of the defects inspection apparatuses1000-1 to 1000-5 are sent to the database 16 to enable free operation ofthe inspected results. In addition, inspection results of the glide test109 and the certify test 110 are also sent to and processed by the dataprocessing unit 60, and subsequently transmitted to the database 16.Note that, in the constitution shown in FIG. 3, each of the defectsinspection apparatuses 1000-1 to 1000-5, the glide test 109 and thecertify test 110 are not shown, however, they are also designed to bedirectly joined to the database 16 without passing through the databaseprocessing unit 60, so as to enable data exchange.

In the present drawing, explanation is given that the inspection 111 iscarried out by the defects inspection apparatus 1000 before and afterthe production step of the medium, however, inspection place may beselected in response to requirement. The defects inspection apparatus1000 used in the inspection 111 before and after each of the steps maybe common, or an exclusive defects inspection apparatus may be installedat each of the steps.

Then, explanation will be given on kinds of defects generating on a disksubstrate. FIG. 4 is a drawing viewed from the surface of the disksubstrate in FIGS. 4 and 5. The foreign matter 72 is one generatingmainly in a production apparatus, such as one floating in air andadheres on the substrate. The scratch 73 is one scratched the substrateby abrasive grains used in the polishing step 108 explained in FIG. 3.The dents or protrusions 74 are those made by missing or protrusion of asurface caused by crystal defects or the like.

FIG. 5 shows a recording method in a hard disk apparatus, and across-sectional view of the disk substrate 1. Signals on the disksubstrate 1 are read or written by the head (magnetic element) 71 formedat the tip of the magnetic head unit 70. Spacing between the disksubstrate 1 and the head for recording and writing is called as theflying height, and recently, it is approaching to several tens nm. Eachof the defects smaller than this flying height does not raise anyproblem, however, larger ones than the flying height bring about thepossibility of missing the head 71. The foreign matter 72, because ofbeing adhered on the surface of the disk substrate 1, bring about thepossibility of interfering with the head 71; the scratch 73, becausebeing mainly protruded one bring about the possibility of interferingwith the head 71; and the dents or protrusions 74 bring about thepossibility of interfering with the head 71 before and after the defectsposition. Therefore, it is necessary to detect these defects by adefects inspection apparatus, and eliminate these as defect products.Note that length and width of the defects are versatile, and thusdefects kinds are differentiated in response to the shape thereof.

First of all, in the case for carrying out defects inspection on a disksubstrate, in any one inspection step among a plurality of inspectionsteps shown in FIG. 3, by using a plurality of defects inspectionapparatuses provided with constitution as explained in FIG. 1, a methodfor confirming defects detection sensitivity among such defectsinspection apparatuses will be explained using FIGS. 6 to 9.

FIG. 6 shows an example of a processing flow showing procedure ofprocessing each of the first inspection data 150 obtained by inspectionof a inspection object sample by the first defects inspection apparatus,and the second inspection data obtained by inspection of the sameinspection object sample by the second defects inspection apparatus,correction and checking, using the data processing unit 152, of positionof data obtained by each of the detection apparatuses. FIGS. 7A to 7Fare drawings map-displaying inspection data in each of the steps in aflow chart explained by FIG. 6.

Firstly, a flow chart shown in FIG. 6 will be explained. As the firstinspection step 150 for processing the first inspected data obtained byinspecting an inspection object sample by the first defects inspectionapparatus, the inspection information input step 153 inputs inspectedinformation. Information to be input includes inherent ID, outer shape,inspection range, inspection surface of a disk substrate to be inspectedor the like. Then, in the detection start step 154, inspection isstarted using the first inspection apparatus. Finally, in the firstinspection result output step 155, the first inspection result is outputto the data processing unit 60. This is the inspected result in responseto defects number explained in FIG. 2. Here, because data of defectsposition to be output as the first inspection result cannot set positionstandard mark on an inspection object disk substrate, a tentativeoriginal point and a base line of a polar coordinate system are set onthe disk substrate in a state of the disk substrate set on the rotationtable 2 in FIG. 1, to extract position information on defects detectedbased on this tentative polar coordinate system.

Then, also in the second inspection step 151 for processing the secondinspected data obtained by inspecting the same sample by the seconddefects inspection apparatus, similarly as in the first inspection step,inspection information similar to the first inspection step is input bythe inspection information input step 156, and inspection is started,using the second inspection apparatus in the inspection start step 157,and finally, by the second inspection result output step 158, the secondinspection result is output to the data processing unit 60.

FIG. 7A shows an example of map-display output as the first inspectionresult 155 in the first inspection step 150. The map 162 is displayed bycoordinates (polar coordinates) of angle (θ) and radius direction (R),to display the defects 163 at each of the coordinate positions.

FIG. 7B shows map-display output as the second inspection result 158 inthe second inspection step 151. The map 164 displays the defects 165 ateach of the coordinate positions (polar coordinates).

Then, in a flow chart of FIG. 6, the data processing step 152 is carriedout by inputting the first inspecting result 155 obtained by inspectingusing the first defects inspection apparatus, and the second inspectingresult 158 obtained by inspecting using the second defects inspectionapparatuses, to the data processing unit 60. In the data processing step152, firstly the rotation position correction 159 is carried out as foroutput from the first inspecting result 155, and the second inspectingresult 158, to correct error of coordinate data of defects positionscaused by misalignment of a coordinate system. This rotation positioncorrection step 159 will be explained using FIGS. 7A to 7F.

Position of the defects 163 detected from the first inspecting result155 in FIG. 7A, and position of the defects 165 detected from the secondinspecting result 158 in FIG. 7B are not necessarily output as the samecoordinate positions, even when common defects each other are present onthe same disk substrate; this is generated because defects positioninformation in the first inspecting result 155 obtained by inspection,using the first defects inspection apparatus, is position information ina polar coordinate system, which is tentatively set on the disksubstrate not having position standard, and therefore does notnecessarily coincide with position information, on a polar coordinatesystem, in a position information in the second inspecting result 158,similarly obtained by inspection using the second defects inspectionapparatus, in view of position of the original point and base line of apolar coordinate system, set on the same disk substrate.

Therefore, in the rotation position correction step 159, based oncoordinates of the first defects position obtained by the firstinspection result 155, as a standard, the rotation position correctionis carried out for correcting position of original point of a polarcoordinate system, and position of base line in a rotation direction,for the coordinates of position of the second defects obtained from thesecond inspection result 158.

FIGS. 8 and 9 show a processing method for carrying out the rotationposition correction, and FIG. 10 shows an example of the step. As aspecific method for this rotation position correction, for example,there is such a method as disclosed in “Method for robust ICPpositioning introduced with M estimation”; Journal of “The Japan Societyfor Precision Engineering”, vol. 67, No. 8, 2001. This rotation positioncorrection method will be explained below.

Firstly, FIG. 10 shows a flow chart for correction of misalignment of arotation direction (θ) of a base line (R) in a R-θ polar coordinatesystem, between the data group A; 200 shown in FIG. 8(a), and the datagroup B; 201 shown in FIG. 8(b), in the case where the data group A;200, namely from defects 202 to 207 are present, as shown in FIG. 8(a),or the data group B; 201, namely from defects 208 to 214 are present asshown in FIG. 8(b), as data obtained from the first inspection result155.

This algorism is for processing in convergence of sequential search forcongruent transformation while updating corresponding relations insidepoints group. The steps 901 to 904 in FIG. 10 will be explained.Distance between defects of the data group A; 200 and the data group B;201 is measured, and the data group A; 200 is matched so as to providethe shortest distance; the detail thereof will be explained by FIG.8(a), (b). Firstly, look at the defect 202 in the data group A; 200. Thedefect present in the data group B; 201, and has the shortest distancefrom the defect 202 is the defect 208; therefore the defect 208 ismatched for the defect 202. Then, a defect in the data group B; 201 islikewise found out for the defect 203; the defect 208 is a defect havingthe shortest distance for also the defect 203. In this way, defects inthe data group B; 201 are set for all of the defects in the data groupA; 200, and each of the distances is calculated so as to convertcoordinates of the data group A; 200, and matched (the steps 901 and902). As a system for determining the distance, a least square methodmay be utilized by conversion of distance (the step 903). FIG. 9 shows amatching result of the data group A; 200, so that sum of distances amongdefects set themselves is shortest. Practically, however, because thedata group A; 200, and the data group B; 201 do not necessarilycoincide, re-matching is carried out between defects of the data groupA; 200, and defects of the data group B; 201. In this case also, asdescribed above, defects closest to the defects of the data group B; 201are determined for the defects of the data group A; 200, and re-matched(the step 904). In the case where coincidence rate, between the defectsthe data group A; 200, and the defects of the data group B; 201, attainsa predetermined value, by repeating this procedure, the step is ended.On the other hand, in the case where it is determined that thecoincidence rate does not attain a predetermined value, the procedurereturns to the step 901 to calculate rotation amount and parallelmovement amount of the data group B; 201, and the step 903 is carriedout.

By carrying out a process flow shown in FIG. 10, the rotation positioncorrection 159 in a processing flow of FIG. 6 is carried out, and FIG.7C shows the map 166 obtained by the result thereof. In the map 166 inFIG. 7C, the defect 165, which is displayed in a polar coordinatesystem, as in FIG. 7B, based on the second inspection result 158 in aprocessing flow shown in FIG. 6, is displayed as the defect 167, bycorrection of position in a rotation direction around an original pointof a polar coordinate, as a center.

Then, the checking processing 160 of defects coordinates is carried out,in a process flow shown in FIG. 6. In the checking processing 160 ofdefects coordinates, coordinates of the defects processed by therotation position correction 159 for the second inspection result 158,and the defects 163 obtained by the first inspection result 155, whichis standard, are checked. FIG. 7D shows the map 168 of the resultchecked. The map 168 displays the coincident defects group 169 and thenon-coincident defects group 170 between the first inspection result 155and the second inspection result 158, or the defect (group) 171determined as being critical based on defects kinds; they may also bechecked based on difference between the first inspection coordinates andthe second detection coordinates, or information weighted in response todefects kinds. In addition, map-display in FIG. 7D can also be displayedin exchanging manner by defects kinds, or furthermore, also a pluralityof defects kinds selected can simultaneously be displayed.

Then, based on this check result, information display is carried out inthe step 161 shown in FIG. 6. FIGS. 7E and 7F show examples ofinformation displayed by the step 161. FIG. 7E is an example displayingthe map 172 of the defects group 173 determined as being coincident bythe defects coordinates checking 160. FIG. 7F is an example displayingthe map 174 of the defects group 175 determined as being non-coincident.In this way, free map-display is possible in response to the cases ofcoincidence, non-coincidence or under other conditions. These displayscan be processed by grouping of defects kinds or degree of coincidenceor the like, as appropriate, and in this way, a state of coincidence ornon-coincidence between inspected data can be displayed.

As in the present embodiment, by making possible displaying positioncoordinates data of defects detected by inspection of the same sample,by each of different inspection apparatuses, after correction ofmisalignment of a polar coordinate system between each of inspectionapparatuses, and then determining coincidence or non-coincidence betweeninspection results, evaluation of defects detection sensitivity of eachof detection apparatuses becomes possible. In addition, by adjustment ofinspection sensitivity using this inspection result, so as to detect thesame defects by each of inspection apparatuses, defects detectionsensitivities among a plurality set of inspection apparatuses can bematched.

In addition, in the present embodiment, explanation was given oncorrection of position data of defects detected in different defectsinspection apparatuses, however, it is also effective in the case ofcorrecting coordinates data of positions of defects detected in eachinspection on the same sample in the same defects inspection apparatus,under the same inspection condition, or under a plurality of differentinspection conditions. In this case, a disk substrate may not be removedfrom a defects inspection apparatus, and standard of inspection data isthe same. Therefore, even when defects positions of inspection data arenot rotated, display of the defects data or the like is the same, exceptthat the processing thereof is omitted. This twice inspection method isapplied to confirmation of reproducibility of an inspection apparatus,or confirmation of condition of the inspection apparatus.

In addition, by carrying out inspection each time this substrate passesthe step explained in FIG. 3, using one disk substrate to be inspected,and by processing this inspected data, a state of increase or decreasein data, or coincidence or non-coincidence between the steps can beunderstood. This method is capable of providing easy confirmation ofcondition in a production apparatus.

In the embodiment explained above, explanation was given on the casewhere defects are detected using a plurality sets of defects inspectionapparatuses in any one inspection step between the inspection stepsbefore or after each of the processing steps shown in FIG. 3, however,the present invention can be applied also to the case where defectsinspection is carried out before and after each of the processing stepsshown in FIG. 3, and the defects data detected is processed.

In this case, the first inspection 150 explained in FIG. 6 is, forexample, an inspection carried out before the texture fabrication 104among processing steps shown in FIG. 3, while the second inspection 151is an inspection carried out after the cleaning 105 for cleaning thesubstrate already subjected to the texture fabrication.

Here, in the case where defects inspection apparatuses used in the firstinspection 150 and the second inspection 151 are not the same, bychecking, in advance, of inspected data detected by each of the defectsinspection apparatuses according to a flow shown in FIG. 6, using thesame disk substrate or a test substrate, so as to match detectionsensitivity, reliability of results by the subsequent steps can furtherbe enhanced.

By processing defects data obtained by inspection in each of theinspection steps, according to a processing flow shown in FIG. 6,defects data detected in each of the inspection steps, and havingrotation position corrected, as shown in FIG. 7D, can be matched andchecked afterward, and a state of defects generation in the texturefabrication 104 can be confirmed.

Similarly in the magnetic substance film formation step 106, thelubrication layer film formation step 107, and the polishing step 108,shown in FIG. 3, by rotation position correction of data in theinspection step before or after thereof, and subsequent checking, astate of defects generation in each of processing steps can beconfirmed.

Furthermore, as the first inspection 150 explained in FIG. 6, as any oneinspection step between inspection steps before or after each of theprocessing steps shown in FIG. 3, inspection data by a separateinspection apparatus such as a glide test, a certify test or the like,may also be used as the second inspection 151 of FIG. 6. Patent document2 has description on a defects inspection of magnetic characteristics ofa magnetic disk; this inspection apparatus is for an inspection methodunder rotation of a disk substrate, and outputs coordinates in arotation direction and a radius direction, as defects information. Inputof inspected results on the magnetic characteristics to the secondinspection 151 explained in FIG. 6 is capable of defects checking withthe first inspection carried out using the defects inspection apparatus1000 explained in the above embodiment; this result is capable ofdetermining coincidence rate between defects in surface inspection andmagnetic characteristics inspection of a disk substrate. From thiscoincidence rate, it is also possible to find out critical defects basedon the result of a surface inspection, and shortening effect ofproduction steps of a disk substrate can be expected.

Note that a map after processing can be displayed on the monitor 14shown in FIG. 1. Furthermore, display by printing using the printer 15is also possible.

Explanation above was given on a disk substrate used in a hardwareapparatus, however, it goes without saying that similar effect can beobtained also in a semiconductor wafer. In surface defects inspection ofa semiconductor wafer after processed to have a flat surface in general(for example, a state of bare wafer, or a wafer after CMP (ChemicalMechanical Polishing) processing), defects positions on a semiconductorwafer are detected using a cut edge (notch) set at the outercircumference of the semiconductor wafer, as standard, however, asexplained in the present invention, overlapping the second inspectionresults using defects positions detected in the first inspection, asstandard, is capable of managing defects.

Furthermore, similar effect can be obtained in any object as long ashaving a circular plate-like shape. In addition, similar effect can alsobe obtained in a disk substrate using regularly arranged patterns in arecording zone, such as a patterned medium used in a hard diskapparatus. In addition, explanation was given on an inspection apparatusof magnetic characteristics, as other kind of an inspection apparatus,however, use of results of an electrical inspection adopted in aninspection of a semiconductor wafer, for example, a fail-bit inspection,is also possible.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiment is therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

1. A method for inspecting a sample, comprising the following steps for:obtaining position information, in a first coordinate system, of a firstdefects group detected by detecting the first defects group on a sample,by inspecting said sample under a first condition; obtaining positioninformation, in a second coordinate system, of a second defects groupdetected by detecting the second defects group on a sample, byinspecting said sample under a second condition; correcting error ofrelative position information on said first defects group and/or saidsecond defects group, which error generating by misalignment betweensaid first coordinate system and said second coordinate system; checkingsaid first defects group and said second defects group, having error ofsaid relative position information corrected; and outputting saidchecked results.
 2. The method for inspecting a sample according toclaim 1, wherein the first defects group on said sample is detected byinspection under said first condition while rotating said sample, in thestep for obtaining position information, in the first coordinate system,of the first defects group on said sample, and the second defects groupon said sample is detected by inspection under said second conditionwhile rotating said sample, in the step for obtaining positioninformation, in the second coordinate system, of the second defectsgroup on said sample.
 3. The method for inspecting a sample according toclaim 1, wherein the information on said first defects group and theinformation on said second defects group, to be subjected to saidchecking, in the step for checking said first defects group and saidsecond defects group, comprise any of defects kinds, defects dimensionand defects detection signal intensity.
 4. The method for inspecting asample according to claim 1, wherein information on coincident defectsis output, as a checking result of said first defects group and saidsecond defects group, having said position information adjusted, in thestep for outputting results of said checking.
 5. The method forinspecting a sample according to claim 1, wherein coincident defects andnon-coincident defects are separately output, as a checking result ofsaid first defects group and said second defects group, having saidposition information adjusted, in the step for outputting results ofsaid checking.
 6. The method for inspecting a sample according to claim1, wherein said first condition in the step for detecting said firstdefects group on said sample, and said second condition in the step fordetecting said second defects group on said sample are the samecondition.
 7. The method for inspecting a sample according to claim 1,wherein said first condition in the step for detecting said firstdefects group on said sample is condition before processing said sample,and said second condition in the step for detecting said second defectsgroup on said sample is condition after processing said sample.
 8. Amethod for inspecting a sample, comprising the following steps for:obtaining position information on a first defects group detected,relative to a first position standard on a sample, by detecting thefirst defects group on said sample by inspecting said sample under afirst condition; obtaining position information on a second defectsgroup detected, relative to a second position standard on a sample, bydetecting the second defects group on said sample by inspecting saidsample under a second condition; calculating misalignment amount betweensaid first position standard and said second position standard, usingposition information on said first defects group, relative to said firstposition standard, and position information on said second defectsgroup, relative to said second position standard; correcting positioninformation on said first defects group and/or position information onsaid second defects group, based on said calculated misalignment amount;checking said first defects group and said second defects group, havingsaid position information corrected; and outputting said checkedresults.
 9. The method for inspecting a sample according to claim 8,wherein the first defects group on said sample is detected by inspectionunder said first condition while rotating said sample, in the step forobtaining position information, in the first coordinate system, of thefirst defects group on said sample, and the second defects group on saidsample is detected by inspection under said second condition whilerotating said sample, in the step for obtaining position information, inthe second coordinate system, of the second defects group on saidsample.
 10. The method for inspecting a sample according to claim 8,wherein the information on said first defects group and the informationon said second defects group, to be subjected to said checking, in thestep for checking said first defects group and said second defectsgroup, comprise any of defects kinds, defects dimension and defectsdetection signal intensity.
 11. The method for inspecting a sampleaccording to claim 8, wherein information on coincident defects isoutput, as a checking result of said first defects group and said seconddefects group, having said position information adjusted, in the stepfor outputting results of said checking.
 12. The method for inspecting asample according to claim 8, wherein coincident defects andnon-coincident defects are separately output, as a checking result ofsaid first defects group and said second defects group, having saidposition information adjusted, in the step for outputting results ofsaid checking.
 13. The method for inspecting a sample according to claim8, wherein said first condition in the step for detecting said firstdefects group on said sample, and said second condition in the step fordetecting said second defects group on said sample are the samecondition.
 14. The method for inspecting a sample according to claim 8,wherein said first condition in the step for detecting said firstdefects group on said sample is condition before processing said sample,and said second condition in the step for detecting said second defectsgroup on said sample is condition after processing said sample.
 15. Anapparatus for inspecting a sample, comprising the followingconstitutions: a table unit for mounting, rotating and as well asmoving, in one axial direction, a sample; a lighting unit forilluminating light from an oblique direction to the sample which ismounted on said table unit and rotating and moving in one axisdirection; a detection unit for detecting, by focusing, scattered lightfrom said sample lighted by said lighting unit; a defects extractionunit for extracting defects present on said sample, by processingsignals detected by said detection unit; a defects informationextraction unit for extracting information on defects extracted by saiddefects extraction unit; a memory unit for memorizing information ondefects extracted previously; a defects information correction unit forcorrecting information on said defects extracted by said defectsinformation extraction unit, and information on defects extractedpreviously, which was memorized in said memory unit; a defectsinformation checking unit for checking information on the defectsextracted by said defects information extraction unit, which wascorrected by said defects information correction unit, and informationon the defects extracted previously, which was memorized in said memoryunit; and an output unit for outputting result checked by said defectsinformation checking unit.
 16. The apparatus for inspecting a sampleaccording to claim 15, wherein the information on defects extracted bysaid defects information extraction unit, and information on defectsextracted previously, which was memorized in said memory unit, whichsets of information are subjected to checking by said defectsinformation checking unit comprise any of defects kinds, defectsdimension and defects detection signal intensity.
 17. The apparatus forinspecting a sample according to claim 15, wherein said output unitoutputs information on coincident defects, as a checking result by saiddefects information checking unit
 18. The apparatus for inspecting asample according to claim 15, wherein said output unit separatelyoutputs coincident defects and non-coincident defects, as a checkingresult by said defects information checking unit.
 19. The apparatus forinspecting a sample according to claim 15, wherein said sample is any ofa disk substrate or a semiconductor wafer for a hard disk apparatus.